Many foam generators are known particularly as in the context of hand cleaner dispensers generating a hand cleaning foam comprising a mixture of air and a foamable hand cleaning fluid. Typical foam generators include one or more screens providing small apertures for passage of the air and fluid therethrough to create turbulence and generate foam. Porous sponges are also used as foam generators. Combinations of screens and porous sponges are known for use as foam generators as, for example, in U.S. Pat. No. 6,601,736 to Ophardt et al, issued Aug. 5, 2003, the disclosure of which is incorporated herein by reference and U.S. Pat. No. 7,337,930 to Ophardt, issued Mar. 4, 2008, the disclosure of which is incorporated herein by reference.
The inventors of the present invention have appreciated that previously known pumps incorporating such foam generators suffer the disadvantages that they are formed from a number of parts, leading to increased costs for manufacture and assembly.
The present inventors have also appreciated that foam generators which utilize such screens and sponges for foam generation typically require supporting structure such as housings which increase the complexity of manufacture and increase the number of parts required to form a foam generator.
U.S. Pat. No. 1,329,559 to Tesla, the disclosure of which is incorporated herein by reference, teaches what is known and is referred to herein as a Tesla valvular conduit which provides for relatively low resistance flow in one direction through the conduit yet high resistance flow in an opposite direction. The present inventors have appreciated that valvular conduits similar to the Tesla valvular conduit have not been configured which are advantageous for ease of construction and manufacture.
Pumps are known for the simultaneous discharge of a liquid from a reservoir bottle and air from the atmosphere. One example of such a pump is U.S. Pat. No. 5,271,530 to Uehira et al, issued Dec. 21, 1993. The inventors of the present invention have appreciated that such previously known pumps suffer the disadvantages that they are formed from a large number of parts, and are complex in their manufacture of the different parts leading to increased costs for manufacture and assembly.
The present inventors have appreciated that pumps are known which use diaphragm members, however, it is appreciated that disadvantages arise in respect of the construction of known diaphragm members so as to facilitate their manufacture and advantageous sealing engagement with other elements of the pumps.